I don't think Real Madrid, Manchester City and Bayern Munich will be making big transfers in January which could really have a big impact on their title chances.
I have mentioned these 3 teams because these teams are the top favourites for the championship in the Champions League (according to bookmakers I mean). I also agree with this classification honestly because they are technically the strongest teams with the best squads. I don't think that any of them will feel any weakness in their squads much. Real Madrid could make a transfer for the defense line though. Because Alaba has also got injured so Ancelotti needs to strengthen the position.
It is likely that Manchester City will add players. because some of its main players such as Erling Haland, Kevin De Bruine are injured.
With the tight schedule of the premiere league and champion league and the tight competition if you don't add players, you will be out of shape.
Both in the English league and the champions league can lose all their titles or cannot defend their titles.